Project Summary: Triple negative breast cancer cells have higher glucose uptake and increased lactate production when compared to estrogen receptor (ER)-expressing cells that have higher mitochondrial respiration. Metabolic phenotype and differences in fuel utilization of the malignant cells may thus contribute to the variable responses to ketogenic diet across cancer types. With focus on the tumor as the primary target, our overarching hypothesis is: A ketogenic diet will slow disease progression more effectively in breast cancers that are predominantly glycolytic when compared to breast cancers with high rates of mitochondrial respiration. We have designed three complementary experimental strategies to investigate the implications of this hypothesis in a syngeneic mouse breast cancer model. In Aim 1, we will metabolically phenotype two triple negative murine mammary tumor cell lines (C0321 ? claudin-low and B5725 ? basal-like) and two murine ER- expressing cell lines (TC4 and TC2). In Aim 2, FVB/N mice will receive isografts consisting either of a tumor cell line with glycolytic phenotype or tumor cells with high rate of mitochondrial respiration. Tumor growth and progression under conditions of a ketogenic diet will be compared to chow-feeding within and between metabolic phenotypes. Two experiments will be performed: Experiment 1 will evaluate the effect of diet on tumor growth after a tumor has been established. In Experiment 2, the mice will consume ketogenic diet before tumor cell transplantation, allowing assessment of the diet's effect on tumor establishment and metastasis. In Aim 3, Using Stable-Isotope Resolved Metabolomics (SIRM), we will track the metabolic fate of labeled fatty acid (13C8-octanoate) in the grafted tumor cells as well as the recipients. We will ascertain tumor metabolic phenotype in vivo, and measure mitochondrial density in tumors and in host liver to define fuel utilization and the extent of host and tumor metabolic adaption to a ketogenic diet. This project takes advantage of the unique resources at Pennington Biomedical Research Center to advance my ability to translate basic science research findings into clinical trials.